Hitherto, as this type of a motion assist device, a human body motion assist device described in, for example, Japanese Patent Application Laid-Open No. 2007-130234 has a main body unit disposed adjacent to the front of a torso from a waist to shoulders. First power transmitting units disposed at the front surfaces of upper leg portions are connected through the intermediary of actuators provided on both sides of the lower portion of the main body unit. Second power transmitting units disposed at the front surfaces of lower leg portions are connected through the intermediary of actuators provided at the bottom ends of the first power transmitting units, and slipper-shaped foot holders are connected to the bottom ends of the second power transmitting units through the intermediary of movable connectors. Further, swingable shoulder members are provided on both sides of the upper portion of the main body unit, and third power transmitting units disposed at the front surfaces of upper arms through the intermediary of actuators disposed at the shoulder members are connected. Fourth power transmitting units disposed at the front surfaces of lower arms are connected to the bottom ends of the third power transmitting units through the intermediary of actuators, and grip-type or glove-shaped hand holders are connected to the distal ends of the fourth power transmitting units through the intermediary of movable connectors. Thus, the power imparted to the power transmitting units from the actuators enables the motion assist device to assist the motion of a physically handicapped person or an aged person or the like wearing the human body motion assist device.